Cell-mediated immunity

The immune system of the body is designed to respond to two different ways. One is the humoral response that corresponds to antibody-mediated response. This is response of the immune system to bacteria, viruses, foreign substances, and antigens that freely circulate in the body. Humoral immunity response, involving the B cells of the immune system, recognizes pathogens and antigens moving freely in the body fluids such as blood. Cell-mediated immunity on the other hand is the activity of the T cells of the immune system. It involves the activation of phagocytes, release of cytokines, and antigen-specific cytotoxic T-lymphocytes. The T cells of the cell-mediated immunity develop in the thymus (located behind the breastbone). Then, they move between the bloodstream and the lymphoid organ till they encounter a specific antigen they were made for. When a T cell encounters its antigen, it turns from a naïve T cell to a T cell capable of destroying infected cells or tumor cells with the help of cytotoxic T cells. This is done by cell-mediated immunity. Type 1 diabetes is an autoimmune disease in which there is destruction of the beta cells of pancreas. Since the beta cells of pancreas produce insulin, there is diabetes mellitus. In people with type 1 diabetes, due to various factors, there is cellular immune reactivity causing beta cell destruction. This process is known to be mediated by T cells. Certain T cells are known to infiltrate the islets of Langerhans (which contains the beta cells) and destroy the beta cells. People with type 2 diabetes are also prone to infections more than non-diabetics. This is due to an innate defect in the immune system and decreased cellular responses including low cytokine response in uncontrolled diabetes. Moreover, there is a decrease in the presence of CD4+ T cells in people with diabetic ketoacidosis. This leads to abnormal metabolic processes and further susceptibility to diabetic ketoacidosis.